I wanted to use a Tru Turn for my Funtana, but was surprised how much weight would be gained by the adapter nut and washer they want you to use to hold it on.
Well, I'm sure I'll get flamed for this but I don't use any fancy (heavy) locknut gizmos on my 4-strokes and have never had a problem. Use at least a 6" wrench on the nut, crank it down good and it ain't commin' off. Everyone is always worried about throwing the prop on a 4-stroke but I see just as many (if not more) props and spinners part ways with 2-strokes. 2-stroke or 4-stroke, you gotta
tighten the nut.